What Does the Motor Oil Grade Represent?

[VanRiley]

Taking 15W-40 and 5W-40 as examples, the meanings represented by motor oil grades are: 1. The 'W' stands for winter. The smaller the number before it, the better the oil's low-temperature fluidity, indicating it can be used in lower ambient temperatures and provides better engine protection during cold starts. 2. 5W represents resistance to external low temperatures of -30°C, while 15W can withstand -15°C. 3. The number after represents the oil's kinematic viscosity at 100°C. The higher the number, the higher the viscosity. Motor oils can be broadly divided into two types based on their base oils: mineral oils and synthetic oils. Synthetic oils are further divided into: full synthetic and semi-synthetic. Full synthetic oil is the highest grade.

[DelElla]

The oil specification is actually quite important. Having driven for over a decade, I'm most concerned about the viscosity grade, like the 5W-30 number combination: The first number, such as 5W, represents the oil's flow capability during winter starts—the smaller the number, the easier it is to start the engine in cold weather without causing hard starts. The second number, like 30, indicates the viscosity level under high-temperature operation—the higher the number, the better it can coat engine components during hot summers or high-speed driving, preventing wear. Additionally, motor oils have API specifications like SN or SP, which denote the oil's cleaning performance and anti-corrosion capability, keeping the engine cleaner and extending its lifespan. Choosing the right specification not only saves fuel but also reduces noise—after switching to a suitable low-viscosity oil, I saved a significant amount on fuel costs annually. Different vehicle types also influence the choice: newer cars suit thinner oils like 0W-20 for efficiency, while older cars benefit from thicker options like 10W-40 to prevent leaks. In short, understanding these numbers helps avoid repair hassles and ensures smoother driving.

[MaddoxRose]

As a DIY oil change enthusiast, I consider motor oil grades as usage guidelines. The first number like 5W indicates low-temperature viscosity, showing how quickly the engine starts smoothly in cold weather (W stands for Winter). The second number 30 represents high-temperature protection - higher numbers mean thicker oil that maintains engine protection in summer heat. API codes like SP denote additive levels that clean deposits and boost performance. For me, the key benefit is fuel economy: low-viscosity oil reduces engine resistance, with my tests showing 10% lower fuel consumption. Just follow your vehicle manual for oil selection, and don't exceed usage periods to prevent oil degradation and leaks.

[CarsonAnn]

I prioritize fuel efficiency and environmental protection, so the numbers in the oil viscosity rating are crucial. The '5W' in 5W-30 indicates easier cold starts, reducing emissions, while the '30' represents stable oil film at high temperatures, protecting the engine from wear. This enhances fuel efficiency and reduces CO2 emissions. Choosing the right viscosity rating ensures more efficient engine operation.

[LeHaven]

When I first bought a car, I knew nothing. A friend pointed out that the oil grade is the secret to protecting the engine: the first number like 5W ensures smooth cold starts in winter, and the second number 30 guarantees safe high-speed driving in summer. This directly affects the engine's lifespan—using the wrong type could seize components and lead to costly repairs. I started learning from the manual and gradually understood.

[Margot]

Comparing the engine oil specifications between my old car and the new one, the changes are significant: the new oil like 0W-20 emphasizes quick cold-start performance and fuel efficiency, while the old 10W-40 focuses more on high-temperature protection. The combination of viscosity grades and upgraded API specifications with advanced additives enhances engine wear resistance. When selecting oil, it's crucial to consider climate conditions and driving habits to avoid potential issues.